分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: Although diffuse interstellar bands (DIBs) were discovered over 100 years ago, for most of them, their origins are still unknown. Investigation on the correlations between different DIBs is an important way to study the behavior and distributions of their carriers. Based on stacking thousands of spectra from the Pristine Inner Galaxy Survey, we study the correlations between two DIBs at 442.8 nm ($\lambda$442.8) and 862.1 nm ($\lambda$862.1), as well as the dust grains, in a range of latitude spanning ${\sim}22^{\circ}$ ($4^{\circ}\,{}\,0.3$ mag. For $|b|\,{>}\,12^{\circ}$, $\lambda$442.8 and $\lambda$862.1 present larger relative strength with respect to the dust grains. A systematic variation of the relative strength between $\lambda$442.8 and $\lambda$862.1 with $|b|$ and $E(B-V)$ concludes that the two DIBs do not share a common carrier. Furthermore, the carrier of $\lambda$862.1 is more abundant at high latitudes than that of $\lambda$442.8. This work can be treated as an example showing the significance and potentials to the DIB research covering a large latitude range.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: Based on the accurate color excess $E_{\rm G_{BP},G_{RP}}$ of more than 4 million stars and $E_{\rm NUV,G_{BP}}$ of more than 1 million stars from \citet{2021ApJS..254...38S}, the distance and the extinction of the molecular clouds in the MBM catalog at $|b|>20^{\circ}$ are studied in combination with the distance measurement of \emph{Gaia}/EDR3. The distance as well as the color excess is determined for 66 molecular clouds. The color excess ratio $E_{\rm G_{BP},G_{RP}}/E_{\rm NUV,G_{BP}}$ is derived for 39 of them, which is obviously larger and implies more small particles at smaller extinction. In addition, the scale height of the dust disk is found to be about 100 pc and becomes large at the anticenter direction due to the disk flaring.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: The dust temperature and mass of the supernova remnants (SNRs) in M31 are estimated by fitting the infrared spectral energy distribution calculated from the images in the Spitzer/IRAC4 and MIPS24, Herschel/PACS70, 100, 160, and Herschel/SPIRE250, 350$\mu$m band. Twenty SNRs with relatively reliable photometry exhibit an average dust temperature of $20.1^{+1.8}_{-1.5}$K, which is higher than the surrounding and indicating the heating effect of supernova explosion. The dust mass of these SNRs ranges from about 100 to 800$ M_{\odot}$, much bigger than the SNRs in the Milky Way. On the other hand, this yields the dust surface density of $0.10^{+0.07}_{-0.04}{ M_{\odot} \rm pc^{-2}}$, about half of the surrounding area, which implies that about half dust in the SNRs is destroyed by the supernova explosion. The dust temperature, the radius, and thus the dust mass all demonstrate that the studied SNRs are old and very likely in the snowplow or even fade away phase because of the limitation by the far distance and observation resolution of M31, and the results can serve as a reference to the final effect of supernova explosion on the surrounding dust.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: The three-dimensional extinction and structure are studied for the Taurus, Orion, Perseus and California molecular clouds based on the LAMOST spectroscopy. Stellar color excess is calculated with the intrinsic color index derived from the atmospheric parameters in the LAMOST DR8 catalog and the observed color index in the Gaia EDR3 and the 2MASS PSC. In combination with the distance from the Gaia EDR3 parallax, the three-dimensional dust extinction maps are retrieved in the color excesses $E_{\rm{G_{BP},G_{RP}}}$ and $E_{\rm{J,K_{S}}}$ with an uncertainty of $\sim$0.03mag and $\sim$0.07mag respectively. The extinction maps successfully separate the clouds that overlap in the sky area and manifest the structure of the individual cloud. Meanwhile, a bow-like structure is found with a distance range from 175pc to 250pc, half of which is a part of the Per-Tau Shell in similar coordinates and distance while the other half is not. Three low-extinction rings are additionally discovered and briefly discussed.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: The dust mass of the well-known supernova remnant (SNR) IC 443 is estimated from both the infrared emission and the visual extinction. With photometry to the images taken by \emph{Spitzer}, \emph{WISE}, \emph{IRAS}, \emph{AKARI} and \emph{Planck}, the spectral energy distribution (SED) of the dust is obtained after subtracting the synchrotron radiation and considering the spectral line emission. The dust mass is derived from fitting the SED by a two-component model, which results in a warm component of the temperature of $\sim$ 53 K and the mass of 0.1 $M_\odot$, and a cold component of the temperature of $\sim 17$ K and the mass of 46 $M_\odot$. On the other hand, the dust mass is derived to be $\sim$ 66 $M_\odot$ from the visual extinction of IC 443 which is identified from the 3D Bayestar extinction map and its coincidence with the infrared emission morphology. Roughly the dust mass derived from the infrared emission and the extinction agree mutually. However, the dust mass derived from the infrared emission can be adjusted to be more consistent with that from the extinction by using different dust opacity property or considering optically thick radiation. In addition, the distribution of dust temperature and mass is analyzed by fitting the SED pixel by pixel.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: The three-dimensional extinction and structure are studied for the Taurus, Orion, Perseus and California molecular clouds based on the LAMOST spectroscopy. Stellar color excess is calculated with the intrinsic color index derived from the atmospheric parameters in the LAMOST DR8 catalog and the observed color index in the Gaia EDR3 and the 2MASS PSC. In combination with the distance from the Gaia EDR3 parallax, the three-dimensional dust extinction maps are retrieved in the color excesses $E_{\rm{G_{BP},G_{RP}}}$ and $E_{\rm{J,K_{S}}}$ with an uncertainty of $\sim$0.03mag and $\sim$0.07mag respectively. The extinction maps successfully separate the clouds that overlap in the sky area and manifest the structure of the individual cloud. Meanwhile, a bow-like structure is found with a distance range from 175pc to 250pc, half of which is a part of the Per-Tau Shell in similar coordinates and distance while the other half is not. Three low-extinction rings are additionally discovered and briefly discussed.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: Although diffuse interstellar bands (DIBs) were discovered over 100 years ago, for most of them, their origins are still unknown. Investigation on the correlations between different DIBs is an important way to study the behavior and distributions of their carriers. Based on stacking thousands of spectra from the Pristine Inner Galaxy Survey, we study the correlations between two DIBs at 442.8 nm ($\lambda$442.8) and 862.1 nm ($\lambda$862.1), as well as the dust grains, in a range of latitude spanning ${\sim}22^{\circ}$ ($4^{\circ}\,{}\,0.3$ mag. For $|b|\,{>}\,12^{\circ}$, $\lambda$442.8 and $\lambda$862.1 present larger relative strength with respect to the dust grains. A systematic variation of the relative strength between $\lambda$442.8 and $\lambda$862.1 with $|b|$ and $E(B-V)$ concludes that the two DIBs do not share a common carrier. Furthermore, the carrier of $\lambda$862.1 is more abundant at high latitudes than that of $\lambda$442.8. This work can be treated as an example showing the significance and potentials to the DIB research covering a large latitude range.
分类: 工程与技术科学 >> 工程与技术科学其他学科 提交时间: 2023-01-03 合作期刊: 《2022年第三届艺术设计、传播与工程科学研讨会》
摘要: According to the characteristics and difficulties of AIDS prevention education, this research adopts a dynamic and static combination method, integrating the original static teaching into VR technology which can be operated, interacted, or even 360detailed learning. Through realizing the functions of scene restoration and detailed interactive operation in order to form a technical framework for VR AIDS prevention education via interactive screen system, physical rendering, and other technologies. Then clarify the focus of teaching by dividing the highlights of AIDS prevention education, and at the same time, according to the requirements of privacy, a Modular division is carried out to achieve a VR AIDS prevention and education system that can be selected and flexibly configured based on the requirements.